Design Flood Calculation Of The Qin River Based On Paleoflood Method

The complexity of hydrological phenomena and the deficiency of hydrological information restrict the development of hydrology theory. Paleoflood method extends flood recurrence to several thousand years and can be used to determine the recurrence interval of large outliers in flood series, so it is helpful in frequency analysis. Slack water deposits are indicators of water level and age of paleoflood. They can be identified using Quaternary Period geology and hydrology, and can be aged using radioactive isotopes or other methods. Then the discharge of paleoflood can be calculated based on resumed channel. This method is the main content of paleoflood study. In this paper, paleoflood method combined with sedimentology and chronology is used to study paleoflood occurred from Holocene Epoch to near present within the Qin River drainage basin, and to find the reasons why the 1482-yr historical flood left an unreasonable water level mark at Jiunutai. The importance of paleoflood study can be seen in this paper.The paper expounds the sedimentology theory of paleoflood and the formation of siack water deposits, and demonstrates the field and experimental characters of slack water deposits. The main methods of dating for slack water deposits are also introduced in this paper.In paleoflood study of the Qin River drainage basin, the difficulty is the determination of the recurrence interval of the 1482-yr flood. So it is the emphasis of this paleoflood study to interpret the formation of 1482-yr flood based on enough physiognomy evidence. The purpose is to determine the recurrence interval of the historical flood. According to the altitude of slack water deposit termination which has fine indicative significance, the water level of a paleoflood can be determined and the discharge of the paleoflood can be calculated using hydraulic model. Then frequency analysis of the Qin River flood series with paleoflood and 1482-yr flood can be successfully done.